Comparative Study of the Microstructure and Properties of Cast-Fabricated and 3D-Printed Laser-Sintered Co–Cr Alloys for Removable Partial Denture Frameworks

Abstract

Since additive technologies in dentistry are gradually replacing metal casting technology, it is necessary to evaluate new dental constructions intended for the development of removable partial denture frameworks. The aim of this research was to evaluate the microstructure and mechanical properties of 3D-printed, laser-melted and -sintered Co–Cr alloys, and perform a comparative study with Co–Cr castings for the same dental purposes. The experiments were divided into two groups. The first group consisted of samples produced by conventional casting of the Co–Cr alloy. The second group consisted of 3D-printed, laser-melted and -sintered specimens produced from a Co–Cr alloy powder divided into three subgroups, depending on the technological parameters chosen for manufacturing (angle, location and heat treatment). Examination of the microstructure was carried out by classical metallographic sample preparation, using optical microscopy and scanning electron microscopy with energy dispersive X-ray spectroscopy (EDX) analysis. A structural phase analysis was also performed by XRD. The mechanical properties were determined using a standard tensile test. The microstructure observation showed a dendritic character in the case of castings, while in the case of 3D-printed, laser-melted and -sintered Co–Cr alloys, the microstructure was typical for additive technologies. The XRD phase analysis confirmed the presence of Co–Cr phases (ε and γ). The results of the tensile test showed remarkably higher yield and tensile strength values and slightly lower elongation of the 3D-printed, laser-melted and -sintered samples than those produced by conventional casting.

Lower Jaw Full-Arch Restoration: A Completely Digital Approach to Immediate Load

“…While the precision achieved using laser sintering and laser melting is an important feature, their impact goes much further. These techniques also offer the use of a wide range of materials, including biocompatible options such as titanium, cobalt-chromium alloys, and specialized dental alloys [26]. This versatility of the materials guarantees that the components that revolve around the implant-supported prosthesis can be developed with specific characteristics for each individual case to satisfy the specific needs of each patient, considering factors such as biocompatibility and resistance [27].…”

Survey and Challenges of Dental Metallic Materials

“…Because CoCr dental alloys are accessible as solid disc blocks for milling, tiny cylinders for casting, or powder for 3D printing, they are commonly employed in all of these processes. CoCr alloys are currently regarded as the preferred material for base-metal dental framework fabrication because its accessibility in dental fabrication processes, clinical performance, affordability, biocompatibility, and mechanical qualities (Presotto et al 2021;Stamenković et al, 2023. ).…”

“…), which improve the desired properties of the material while reducing or eliminating harmful properties. Modern intensive plastic deformation procedures have recently been used to produce fine-grained metal materials with improved mechanical properties when compared to materials produced using traditional manufacturing methods, though the question of their corrosion resistance and biocompatibility remains open (Stamenković et al, 2023). Given that metallic biomaterials are in long-term intimate contact with living tissues, it is possible to conclude that knowledge and understanding of the interactions between the implant material's surface and human tissues is extremely important for the development of new materials for use in medicine, and thus the material's non-toxicity and biocompatibility become critical factors in the further development of implant metallic materials (Slokar et al, 2017;de Matos, et al, 2021;Anusavice, 2013;Asakura, 2012)…”

“…Another advantage is the creation of titanium dioxide (TiO 2 ) on the surface of Ti, which possesses bioactive qualities that promote new bone growth. Cobalt-based alloys (e.g., Co-Cr-Mo) have excellent mechanical and biocompatible properties (Stamenković et al, 2023) whereas stainless steels (Standard, I. S. O., 2007) have recently been abandoned due to insufficient corrosion resistance and the effects of the body's hypersensitivity to nickel (Ni), which is released due to steel implant and body fluids interaction.…”

review article: CAD-CAM in removable dental prosthesis

“…The most used material is metal. The most commonly used additive technologies in RPD are selective laser melting (SLM) sintering and direct metal laser sintering (DMLS), RPDs fabricated with these systems fit very precisely to the supporting tissues of partially edentulous patients (Stamenković et al, 2023).…”